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Re: [Qemu-devel] [PATCH, RFC] More than 2G of memory on 64-bit hosts


From: Julian Seward
Subject: Re: [Qemu-devel] [PATCH, RFC] More than 2G of memory on 64-bit hosts
Date: Wed, 27 Jun 2007 11:32:51 +0100
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> > Unfortunately C99 relaxed this requirement, and allowed abominations like
> > the win64 ABI.
> >
> > This means you have a choice: Write standard conforming code (long) that
> > works on all known systems except win64, or use features that do't exist
> > on many systems. IIRC C99 types like intptr_t are not supported on
> > several fairly common unix systems.
>
> In that case I'll vote for unsigned long. I'd pass the issue to those
> doing a win64 port, if ever that happens.

In Valgrind-world we use an alternative approach, which is to typedef
a set of new integral types and use those exclusively, and not use the
native 'int', 'long' etc.  The new types have a single fixed meaning
regardless of the host or guest and it is up to the configure script
to set up suitable typedefs.  At startup Valgrind checks the size and
signedness of these types is as expected, so any configuration errors
are caught.  This has proved very helpful in porting to a number of 
platforms.

J




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